A new genus and species, Hummelinckiella borinquensis n.gen. & n.sp. has been discovered in sediments from shallow water off Puerto Rico, the Dominican Republic, and Grand Turk (Turks & Caicos Islands). Because of the striking sculpture of its protoconch, it is placed in a new genus of the subfamily Stephopominae.The only other known western Atlantic member of the Stephopominae is Stephopoma myrakeenae Olsson & McGinty, 1958 recorded from the eastern Caribbean (Leeward Islands), herewith invalidating the “paciphile” status of this species and genus, and casting doubts on the value of the “Blasian Subregion”, indicated by Petuch (1990) as a biogeographical unit.